1. Field of the Invention
The invention relates to sliding surfaces and more particularly, it relates to the hydrostatic lubrication of sliding surface bearings.
2. Description of the Prior Art
The invention is described within the environment of axial cylinder internal combustion engines. Of course, while the preferred embodiment has been described in this manner, the use of the invention for sliding surface bearings within a multitude of other embodiments, is to be expected. It is common practice when applying fluid lubricants to some sliding surface bearings, to pump lubricant between the surfaces at pressures exceeding the pressure created by the load on the sliding elements. The bearings using this type of pressurized lubricant, are called "hydrostatic" bearings. In such bearings, the high pressure lubricant supply maintains a relatively thick film of lubricant between the sliding surfaces and very low coefficients of friction result. However, the total power loss with such bearings must include the power required to pump the lubricant. Since this pumping-power loss can be three or four times greater than the frictional power loss that is being overcome, the resultant efficiency of this type of bearing is significantly reduced.
Many styles of axial cylinder internal combustion engines have been developed wherein the cylinders are parallel to, and equi-distant from, the main engine shaft. Such machines have been known in the past as barrel engines or simply round engines, because their distinguishing characteristic is the circular or cylindrical arrangement of the elements. Frequently, these engines are designed for conventional four cycle operation. A cylindrical cam couples the pistons to the drive shaft. Where ridge cams are used, cam followers on each piston track the radial surfaces of the rotating cam.
These engines contain inherent advantages of low cost, light weight, and small volume. Nevertheless, they have not been commercially successful. In axial cylinder engines, sharp load reversals are experienced by the reciprocating pistons, and such load reversals, particularly where accompanied by excessive clearance requirements, result in hammering contact at mating surfaces, noisy operation, and short life. To a large extent, the past deficiencies of these engines can be traced to the relatively large variations in the clearances among the mating parts due to manufacturing tolerances, thermal distortions and wear.